Ben.Miller@ApexGMAT wrote:Severe hardware and software problems is a plural.

This means that the pronoun reflecting it ('that' in A) would need to be plural (ie those) if used at all. This plural aspect helps us eliminate both A and E.

The secondary insight is that the pronoun makes the sentence less concise.

C and D both suffer from the bulky (to those of a) as opposed to B's (to a). This simpler phrasing is allowed by rephrasing the bulky language as a possessive (wristwatch's), which is always allowed as long as it does not change the meaning of the sentence.

Ben

EducationAisle wrote:Well, the easiest way to identify subject is that the subject is (by definition) the doer of the verb. So, the way you identify subject is:

1. Identify the verb
2. Identify the doer of the verb - the Subject

In this case, the verb is had and the doer of had is first personal computers. So, that is the subject.

By the way, C, D and E are incorrect because these choices seem to suggest that hardware and software limitations were unable to perform the complex operations...this is clearly absurd.

Between A and B, A looses out because it says that of a modern wristwatch. It should have been those of a modern wristwatch, because the intention is to refer to limitations (plural). that, when used as a demonstrative pronoun (the way it is used here) can only refer to singular nouns.

By the way, this question seems to be a rip-off of the following GMATprep problem:

Neanderthals had a vocal tract that resembled those of the apes and so were probably without language, a shortcoming that may explain why they were supplanted by our own species.